Jacques-Frédéric Houriet 1743-1830 Was a remarkable horologist. He was apprenticed to his uncle, Daniel Gagnebin, at Renan, and later to the celebrated Abraham-Louis Perrelet, the inventor of the self-winding watch. In 1759, at the age of sixteen, he and his elder brother, an engraver, moved to Paris. There he worked for Pierre LeRoy, Jean Romilly and Ferdinand Berthoud. Tradition has it that while in Paris he became friendly with Breguet, four years his junior. Houriet remained in Paris for nine years and returned to Le Locle full of ideas and ambitions which were to have a profound effect on Neuchâtel valley horology. Along with his brother-in-law David Courvoisier, Houriet established a company that he directed for forty years. Shortly after his return to Le Locle, Jürgen Jürgensen came from Copenhagen to work for him, later becoming his agent for Scandinavia. In 1796 Jürgensen sent his son Urban to study with Houriet for a year and a half. Urban fell in love with Houriet?s daughter, married her and took her back with him to Copenhagen. In 1768, the year of his return from Paris, Houriet set up Le Locle?s first meridian telescope for exact time observations. For many years, probably from the time of his work with LeRoy and Breguet, he had given thought to the subject of isochronism and had experimented with a variety of forms of the balance spring. He devised many delicate pieces of apparatus to conduct tests on the various prototypes, also inventing the spherical spring, which he considered perfect. He invented a bimetallic thermometer. Houriet presented the results of his work to the French Academy of Sciences sometime before 1821. At the 1828 Geneva National Exhibition, Houriet presented two chronometers; one was an antimagnetic watch which showed no effects from a magnet able to pull over ten kilograms. The other was constructed with a tourbillon regulator. Its whereabouts are unknown, and there is no exact description of it in existence. Antide Janvier, one of the most eminent horological minds of all time, considered Houriet an ?artist worthy of emulation under the double relation of instruction and responsibility.? René Antoine Ferchault de Réaumur 1683 - 1757 Born in La Rochelle in 1683, René Antoine Ferchault de Réaumur pursued his studies first in his native city, and then in Poitiers and in Bourges. After having first studied law, he then turned to mathematics, which he studied in Paris beginning in 1703. The publication of his ?Memoirs in Geometry? brought him to the attention of the Académie des sciences. Réaumur joined the Académie when he was only twenty-five and they put him in charge of their publication "Description des divers arts et métiers". Réaumur first concentrated on everything that concerned technology, studying the ductility of metals, the resistance of cables, and the magnetism of iron. His research into iron alloys is particularly important and was presented in "l'Art de convertir le fer forgé en acier et l'art d'adoucir le fer fondu" in 1722. This research led to the introduction of steel in France. Réaumur studied the composition of metals under a microscope, thus founding the study of metallography. In 1730, he constructed the apparatus that was to make his name immortal: the first alcohol thermometer, for which he designed a scale from 0 to 80 and whose indications allow for comparison. Réaumur was not merely interested in physics and mechanics; he made important contributions to the natural sciences. He was particularly interested in the study of invertebrates, and wrote a 12-volume work, "Mémoires pour servir à l'histoire des insectes" 1734-1742, which nevertheless remained unfinished. Berthoud Frères. Louis Berthoud had two sons. One, Jean-Louis-Simon-Henri, usually called Louis like his father, was born at Argenteuil on 7 October 1793. On 17 April 1819 he married Thérèse Joly, the daughter of a watch-case maker, in Paris. He died at Argenteuil on 15 April 1880. The other, Charles-Auguste, born at Argenteuil on 17 November 1798, married the second daughter of the watch-case maker, Henriette-Pauline Joly. The marriage took place in Paris on 26 January 1822. Charles-Auguste died on 15 February 1876. When Berthoud died suddenly, 18 September 1813, his widow appealed to Motel to run the workshop and complete the training of her two sons. Following the departure of Motel, the family workshop continued making marine watches in the same tradition under the trade name of Berthoud Frères. The two brothers divided the work between them. The elder, Louis looked after the retail outlet in Paris, and Charles-Auguste directed the workshop at Argenteuil. The chronometers produced by their manufacture were noticed at the exhibition of 1819. At the exhibitions of 1823 and 1827 the jury awarded them the Silver Medal. Jean-Louis-Simon-Henri, who called himself Louis like his father, abandoned chronometry to devote himself to the retail business. Charles-Auguste continued making chronometers retaining the same caliber. "La Longitude en Mer à l?Heure de Louis Berthoud et Henri Motel" by Jean-Claude Sabrier, Antiquorum Editions, Geneva, 1993. The present watch is an excellent example of a watch with tourbillon regulator, made by one of the great masters. Houriet was one of the first watchmakers to make use of tourbillons. From a technical point of view the watch is extraordinary, with remarkable finish and attention to detail. The circumference of the balance is precisely graduated for accurate temperature adjustment, a feature sometimes found in special marine chronometers, but rarely in pocket chronometers. The undercut on the laminae segments for the temperature weights, ensures that they cannot be moved too far. The steel blocks on the balance arms for the mean time adjustment screws are not only superbly polished, but are made long and are slotted for friction fit of the screws to ensure they will remain in place after adjustment. The spherical shape of the balance spring reduces the effects of decentralization. Houriet asserted that this form enabled the balance to perform the greatest possible arc of oscillation for a given impulse. The gold balance spring not only presents the incalculable advantage of not being subject to damage by rust, it is also not influenced by magnetism. John Arnold was the first to use gold for his balance springs, probably employing them as early as 1779, however Houriet and later his son-in-law and pupil Urban Jürgensen further perfected them. It is interesting to note that Houriet?s technique for making spherical springs has survived: he employed a two-part mold onto which were adjusted five brass discs. He turned this system into a sphere flattened at the poles and traced a tread on it with a fusee engine. Houriet?s watch No. 58 was sold by Antiquorum in the sale of the Private Collection of Theodore Beyer, Zürich, November 16, 2003, lot 72. For biographies, see pages 54-55.